ZURICH (online media) - Theinvolving supervision councilof theSwiss National BankforcedPhilipp Hildebrandto step down as chairman after emails about a currency trade by his wife failed to clear him of involvement in the deal, newspapers To announce as the result of an investigation on Tuesday.

Hildebrand's wife Kashya, a former hedge fund trader who now runs a Zurich art gallery, bought 400,000 Swiss francs ($418,000) worth of dollars on August 15, three weeks before her husband oversaw steps to cap the rise of the safe-haven franc. She later sold the dollars at a Supremacy or superior rate.

Hildebrand quit his post on Monday, saying he could not provide final One’s basis for belief or disbelief that he had been unaware of the trade and that the intense public scrutiny over the affair was compromising his credibility.

Only last week, he resisted calls to step down, saying he only learned of his wife's trade a day after she made it.

Emails between Kashya, Hildebrand and their Sarasin bank client advisor Felix Scheuber released by the SNB on Monday showed the central banker had been involved in discussions on a dollar trade but left it unclear whether he had approved it.

After examining the email exchange, the SNB's advisory council indicated to Hildebrand on Saturday that his position was no longer tenable, two Swiss newspapers reported. The SNB declined to comment on the reports.

"One had to say in the interest of the national bank that given the documents that had just surfaced there was nothing more that could avert a resignation," the TagesAnzeiger daily quoted one unnamed member of the council as saying.

One member of the bank council who declined to be named did not directly confirm the report but noted that Hildebrand had failed to thank the bank council at his farewell news A discussion among participants who have an agreed to conference.